568
FXUS66 KSTO 192106
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
106 PM PST FRI DEC 19 2025
FOR ADDITIONAL DETAILS ON WEATHER AND EXPECTED IMPACTS OVER THE
NEXT 7 DAYS, PLEASE VISIT WEATHER.GOV/STO/BRIEFING.
KEY MESSAGES
- A PROLONGED PATTERN OF WET AND UNSETTLED WEATHER IS EXPECTED
INTO NEXT WEEK.
- MINOR IMPACTS TONIGHT AND SATURDAY.
- MODERATE TO HEAVY RAIN STARTING SATURDAY NIGHT OFF AN ON
THROUGH CHRISTMAS.
- THOUGH EXACT DETAILS REMAIN UNCERTAIN THIS FAR OUT, THERE IS
THE POTENTIAL FOR MAJOR IMPACTS TO MOUNTAIN TRAVEL DUE TO HEAVY
SNOW BY MID-WEEK (CHRISTMAS EVE AND CHRISTMAS DAY).
DISCUSSION
..TONIGHT AND SATURDAY
A BAND OF PRECIPITATION WILL MOVE FROM NORTH TO SOUTH ACROSS THE
AREA TONIGHT AND SLOWLY DECREASE IN STRENGTH OVER THE SACRAMENTO
AREA LATER THIS EVENING. NO IMPACTS EXPECTED FROM THIS. SATURDAY
STILL SOME MOISTURE STREAMING INTO THE AREA FOR SOME LIGHT SHOWERS
ACROSS MAINLY ALONG THE INTERSTATE 80 AND HIGHWAY 50 CORRIDOR.
SNOW LEVELS WILL BE INCREASING THROUGH THE DAY SO LITTLE TO NO
IMPACTS FROM SNOW DURING THIS PERIOD.
..LATE SATURDAY/SUNDAY - CHRISTMAS DAY
A MODERATELY STRONG ATMOSPHERIC RIVER IS STILL ON TRACK TO PUSH
SEVERAL WAVES OF RAIN OVER THE AREA. AR LANDFALL TOOLS SHOWING A
NICE EAST WEST TAIL OF IVT VALUES THAT LINES UP TO IMPACT THE
FORECAST AREA. CONFIDENCE IS HIGH WITH SOME UNCERTAINITY ONLY IN
THE SOUTHERN LINE OF IT WHICH AT THIS TIME LOOKS TO BE RIGHT
AROUND SACRAMENTO. SOUTH OF THAT LINE PRECIPITATION AMOUNTS COULD
BE NOTABLY LOWER. ENSEMBLE SYSTEMS HAVE BEEN CONSISTENT WITH THE
AREA AND LINES UP WELL WITH WPC EXCESSIVE RAIN OUTLOOKS RIGHT OVER
CENTRAL CALIFORNIA.
MAIN IMPACTS FROM THIS STORM STILL LOOK TO BE THE HEAVY RAIN WHICH
WHEN IT IS ALL OVER HAS THE HEAVIEST AMOUNTS IN THE HIGHER TERRAIN
OF BUTTE COUNTY WHERE PROBABILITIES OF 10 INCHES IS AROUND 90%.
ELSEWHERE FROM 3 TO 8 INCHES LOOKS LIKELY. THE RAIN WILL HAVE
HEAVIER PERIODS OFF AN ON DURING THIS STRETCH. AT THIS TIME, WE
BELIEVE MAIN STEM RIVER FLOODING IS NOT AT RISK BUT WE WILL HAVE
TO KEEP AN EYE ON THAT IS THE AR HAPPENS TO HIT ONE AREA LONGER
THEN EXPECTED. WE HAVE ISSUED A AREAL FLOOD WATCH FOR THE ENTIRE
AREA TO COVER FOR URBAN, SMALL STREAMS AND CREEKS FLOODING THAT IS
LIKELY.
HOLIDAY TRAFFICE IMPACTS ALSO SEEM LIKELY. WE HAVE ISSUED A WINTER
STORM WATCH FOR THE TAIL END OF THE STORM AS SNOW LEVELS
EVENTUALLY FALL TO AROUND 5500 TO 6000 FEET STARTING TUESDAY
EVENING THROUGH FRIDAY. CURRENT PROBABILITIES SHOWING A HIGH
(GREAT THEN 80%) CHANCE OF 30" ABOVE 5500 FEET. ONCE IT GETS
CLOSER WE WILL GET MORE EXACT AMOUNTS IN THE FORECAST AS SNOW
LEVEL FLUCUATIONS OFTEN OCCUR WITH THESE SYSTEMS BUT SEVERAL FEET
OF SNOW SEEMS LIKELY.
LAST IMPACT WOULD BE WIND WITH THIS SYSTEM. IT WILL BE GUSTY AT
TIME THROUGHOUT, BUT WEDNESDAY IS STANDING OUT AS THE STRONGEST
DAY. EFI VALUES IN THE MODERATE RANGE ON WEDNESDAY AND NBM
PROBABILITIES SUGGEST A GREATER THEN 50% CHANCE OF WIND GUST FROM
35 TO 45 MPH ON WEDNESDAY.
WR
AVIATION
CEILINGS PRIMARILY REMAIN IFR/MVFR THROUGH THE TAF PERIOD.
VISIBILITIES MAY LOWER TO MVFR PERIODICALLY DUE TO RAIN. HEAVIEST
RAIN RATES ARE EXPECTED AFTER 00Z SUNDAY. SOUTHERLY TO
SOUTHWESTERLY WINDS WITH SUSTAINED SPEEDS GENERALLY 12 KTS OR LESS
THROUGHOUT THE TAF PERIOD, WITH LINGERING GUSTS UP TO 25 KTS
THROUGH 06Z SATURDAY.
STO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH FROM SATURDAY AFTERNOON THROUGH FRIDAY AFTERNOON FOR
BURNEY BASIN / EASTERN SHASTA COUNTY-CARQUINEZ STRAIT AND DELTA-
CENTRAL SACRAMENTO VALLEY-MOTHERLODE-MOUNTAINS SOUTHWESTERN
SHASTA COUNTY TO WESTERN COLUSA COUNTY-NORTHEAST
FOOTHILLS/SACRAMENTO VALLEY-NORTHERN SACRAMENTO VALLEY-NORTHERN
SAN JOAQUIN VALLEY-SHASTA LAKE AREA / NORTHERN SHASTA COUNTY-
SOUTHERN SACRAMENTO VALLEY-WEST SLOPE NORTHERN SIERRA NEVADA-
WESTERN PLUMAS COUNTY/LASSEN PARK.
WINTER STORM WATCH FROM TUESDAY EVENING THROUGH FRIDAY MORNING
FOR WEST SLOPE NORTHERN SIERRA NEVADA-WESTERN PLUMAS
COUNTY/LASSEN PARK.
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